Substance use Disorders and Co-Occurring Psychiatric Disorders: Pharmacotherapeutic Challenges and Integrated Clinical Management-Comprehensive Narrative Review

Substance use disorders (SUDs) commonly occur with psychiatric disorders and can make diagnosis and treatment more difficult. Poor adherence, drug interactions, adverse effects, polypharmacy, and relapse are common challenges. This review discusses the pharmacological management of alcohol, opioid, stimulant, cannabis, and nicotine use disorders in patients with depression, bipolar disorder, schizophrenia, anxiety, and ADHD. Pharmacotherapy is well established for alcohol and opioid use disorders, while treatment options for stimulant and cannabis use disorders are more limited. Safe treatment requires careful monitoring of drug interactions, organ function, adverse effects, and medication adherence. Clinical pharmacists can support medication reviews, patient counselling, adherence monitoring, and adverse drug reaction management. An integrated approach combining pharmacotherapy, psychosocial care, and harm reduction is important for improving patient outcomes.